JP2016133905A - Luminaire and living matter authentication device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a luminaire capable of making distribution of light intensity in an illumination area uniform.SOLUTION: The luminaire comprises: a light source for irradiating an illumination area with light; and a diffraction optical element disposed between the illumination area and the light source, and in which plural diffraction gratings are disposed in a two-dimensional state, in which distribution of a grating interval of the plural diffraction gratings along a predetermined line in the two-dimensional arrangement plane on the diffraction optical element, is configured so that the grating interval is wider on a center side than on an end side.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an illumination device and a biometric authentication device.

  2. Description of the Related Art In recent years, biometric authentication technology has been developed that authenticates a user of a system in a contactless manner based on a biometric image representing biometric information such as a hand or finger vein pattern or a fingerprint or palm print pattern. A biometric authentication device using biometric authentication technology collates an input biometric image representing a user's biometric information with registered biometric information representing a registered user's biometric image registered in advance. The biometric authentication device authenticates a user having biometric information represented by the input biometric information determined to match the registered biometric information based on the result of the verification process as a registered user having a legitimate authority, and Allow the use of. For example, the biometric authentication device may be incorporated in the above system, or may be externally connected to the above system.

  The biometric authentication device is used in various fields such as log-on management to a personal computer (PC), identity verification in a bank ATM (Automated Teller Machine), and entrance / exit management in an office.

  In order for the biometric authentication device to collate users with high accuracy, it is desirable that the characteristic structure of the biometric information is clearly shown on the biometric image. Therefore, a sensor for a biometric authentication apparatus that captures biometric information and generates a biometric image is used as a photographing optical system that captures a subject such as a hand containing biometric information with an imaging lens and an imaging element such as a CCD (Charge Coupled Device). In addition, there may be an illumination optical system that irradiates the subject with illumination light.

  Techniques of a biometric authentication device sensor including an illumination optical system and a photographing optical system have been proposed (for example, Patent Document 1, Patent Document 2, and Patent Document 3).

JP 2009-31903 A JP 2013-130981 A JP 2005-527874 A

  In the conventional method, it is difficult to uniformly illuminate a subject such as a hand with an illumination optical system.

  Accordingly, in one aspect, an object of the present invention is to provide an illumination device and a biometric authentication device that can achieve uniform light intensity distribution in an illumination region.

According to one aspect, a light source that irradiates the illumination area with light;
A diffractive optical element provided between the illumination region and the light source and having a plurality of diffraction gratings arranged two-dimensionally;
An illumination device is provided in which the distribution of the grating spacing of the plurality of diffraction gratings along a predetermined line in a two-dimensional arrangement plane of the diffractive optical element has a characteristic that the grating spacing is wider on the center side than on the end side. The

  An illumination device and a biometric authentication device that can achieve uniform light intensity distribution in the illumination region are obtained.

It is a figure explaining the 1st example of the sensor for biometrics authentication devices. It is a figure explaining the 2nd example of the sensor for biometrics authentication apparatuses. It is a figure which shows typically an example of the illuminating device in 1st Example by sectional view. It is a figure which shows the example of the aggregate | assembly with which the several diffraction grating was arrange | positioned two-dimensionally. 6 is a diagram illustrating an example of a distribution characteristic of a grating interval of the diffractive optical element 26. FIG. It is a figure which shows typically distribution of the light intensity of the nth-order diffracted light directed to the illumination area | region 33. FIG. It is a figure which shows distribution of the light intensity in the illumination area | region 33. FIG. It is a figure which shows distribution of the grating | lattice space | interval along the X direction of diffractive optical element 26 '. It is a figure which shows typically distribution of the light intensity of the nth-order diffracted light directed to the illumination area | region 33 by the diffractive optical element 26 '. It is a figure which shows an example of the illuminating device in 2nd Example typically by sectional view. It is a figure which shows an example of the distribution characteristic of the light intensity in the illumination area | region 33 obtained by the illuminating device 100A. It is a figure which shows another example of the distribution characteristic of the light intensity in the illumination area | region 33 obtained by 100 A of illuminating devices. It is explanatory drawing of 100 A of illuminating devices when the characteristic of FIG. 12 is acquired. It is a figure which shows roughly an example of the sensor for biometrics apparatuses incorporating the illuminating device 100 by a top view. It is a figure which shows roughly an example of the board | substrate 261 containing the diffractive optical element 26 by upper surface view. It is sectional drawing along line AA of FIG. It is a figure which shows schematically another example of the sensor for biometrics apparatuses incorporating the illuminating device 100 by a top view. It is a figure which shows roughly another example of the sensor for biometrics apparatuses incorporating the illuminating device 100 by a top view. It is a figure which shows typically an example of the illuminating device in 3rd Example by sectional view. It is a figure which shows an example of the distribution characteristic of the grating | lattice space | interval of the diffractive optical element 26B. It is a figure which shows an example of the distribution characteristic of the grating | lattice space | interval of the diffractive optical element 26B. It is a figure which shows roughly an example of the sensor for biometrics apparatuses incorporating the illuminating device 100B in top view. It is a figure which shows roughly an example of the board | substrate 261B containing the diffractive optical element 26B by a top view. It is sectional drawing along line BB of FIG. It is a figure which shows roughly another example of the sensor for biometrics apparatuses incorporating the illuminating device 100B in top view. It is a figure which shows schematically another example of the sensor for biometrics apparatuses incorporating the illuminating device 100B in top view. It is a block diagram which shows an example of a biometrics authentication apparatus. It is a block diagram which shows an example of a structure of a computer.

  Hereinafter, embodiments will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram illustrating a first example of a biometric authentication device sensor. In FIG. 1, (a) is a top view of the biometric authentication device sensor, (b) is a schematic side view of the biometric authentication device sensor, and (c) is a schematic diagram illustrating illumination light and illumination distribution of the illumination device sensor. It is. The biometric authentication device sensor 1 </ b> A includes a photographing optical system 2 such as a camera and an illumination optical system 3. The illumination optical system 3 includes a plurality (eight in this example) of LEDs (Light-Emitting Diodes) 5 provided on the substrate 4 and a lens array 6. In this example, as shown in FIG. 1A, the LEDs 5 are arranged in a ring shape outside the photographing optical system 2, and the lens array 6 is provided in a ring shape so as to face the LEDs 5. .

  As shown in FIG. 1C, the illumination light from each LED 5 is spread by the lens array 6 and is applied to the illumination area 10. As shown in the upper part of (c) in FIG. 1, the intensity (arbitrary unit) of the illumination light varies depending on the position (arbitrary unit) on the illumination region 10, and in this example, at the central portion of the illumination region 10. Is higher than the light intensity in other parts of the illumination area 10. As described above, a brightness / darkness distribution is generated in the illumination area 10 according to the arrangement of the LEDs 5 and the characteristics of the lens array 6, and it is difficult to make the intensity distribution of the illuminated illumination light uniform.

  FIG. 2 is a diagram illustrating a second example of the biometric authentication device sensor. 2A is a top view of the biometric authentication device sensor, FIG. 2B is a schematic side view of the biometric authentication device sensor, and FIG. 2C is a schematic diagram illustrating illumination light and illumination distribution of the illumination device sensor. It is. In FIG. 2, the same parts as those of FIG. In the biometric authentication device sensor 1 </ b> B shown in FIG. 2, a diffusion light guide plate 7 is provided in a ring shape so as to face the LEDs 5 instead of the lens array 6 of FIG. 1. As shown in FIG. 2C, the illumination light from each LED 5 is diffused by the diffusion light guide plate 7 and applied to the illumination area 10. As shown in the upper part of FIG. 2C, the intensity (arbitrary unit) of the illumination light is substantially uniform regardless of the position (arbitrary unit) on the illumination region 10. However, the diffused illumination light is applied to a wider area than the illumination area 10, and outside the illumination area 10, waste due to leaked light increases as shown by an ellipse in FIG. As a result, the intensity of illumination light decreases. In order to prevent a decrease in illumination light, it is conceivable to increase the number of LEDs 5 or use a high-power LED. However, increasing the number of LEDs 5 increases the size of the illumination optical system 3. Further, when a high-power LED is used as the LED 5, the illumination optical system 3 is increased in size because the high-power LED is generally relatively large for heat countermeasures.

  Therefore, in the embodiment described below, the illumination device is intended to make the intensity distribution of illumination light uniform in the illumination area. Further, in the embodiment described below, the biometric authentication device is prevented from being deteriorated in authentication accuracy.

  FIG. 3 is a diagram schematically showing an example of the illumination device in the first embodiment in cross-sectional view. In FIG. 3, an example of the illumination device according to the first embodiment is indicated by reference numeral “100”. In FIG. 3, X, Y, and Z directions are defined as three directions orthogonal to each other. Further, in FIG. 3, the spread of light from the diffractive optical element 26 toward the illumination region 33 is schematically indicated by a hatching range S. In the description of the first embodiment, it is assumed that the optical axis of the light source 25, the optical axis of the diffractive optical element 26, and the principal ray emitted from the center of the diffractive optical element 26 coincide.

  In FIG. 3, the illumination region 33 is schematically shown in a cross-sectional view.

  The outer shape and size of the illumination area 33 are arbitrary, but are typically determined according to the outer shape and size of the body part to be authenticated. For example, when a non-contact type authentication method is used, the illumination area 33 may be an assumed area where a living body part should be located at the time of authentication. On the other hand, when the contact-type authentication method is used, the illumination region 33 can be a part (for example, a mounting table formed of a material such as transparent glass) that comes into contact with a part of the living body. Note that the size of the illumination region 33 is significantly larger than the size of the diffraction region of the diffractive optical element 26 and the size of the exit surface of the light source 25. In the following, it is assumed that the illumination area 33 is a planar rectangular area that extends parallel to the XY plane as an example.

  The illumination device 100 includes a light source 25 and a diffractive optical element 26.

  The light source 25 irradiates the illumination area 33 with light. The optical axis of the light source 25 is indicated by symbol I. In the illustrated example, the optical axis I is perpendicular to the illumination area 33 (ie, parallel to the Z direction). The light source 25 is preferably a divergent light source such as an LED rather than a light source that generates light that maintains straightness and parallelism such as laser light. The light source 25 is formed of, for example, an LED (for example, a near infrared LED or a white LED).

  The diffractive optical element 26 is provided between the illumination region 33 and the light source 25. The diffractive optical element 26 is formed by an aggregate (see FIG. 4) in which a plurality of diffraction gratings are two-dimensionally arranged. In the example shown in FIG. 3, the two-dimensional arrangement surface extends in parallel to the XY plane. The center of the two-dimensional arrangement surface of the diffractive optical element 26 (hereinafter also referred to as “the center of the diffractive optical element 26”) is disposed on the optical axis of the light source 25.

  In the example shown in FIG. 3, as an example, the illumination area 33 is a rectangle having a size of 110 mm × 110 mm, and the distance between the light source 25 and the diffractive optical element 26 is 6 mm. The distance between the illumination region 33 and the diffractive optical element 26 is 51 mm in the Z direction.

  FIG. 4 is a top view showing an example of the diffraction grating of the diffractive optical element. In FIG. 4, the diffraction grating is not shown except for the central portion of the diffractive optical element 26. In this example, the diffractive optical element 26 includes a plurality of diffraction gratings (hereinafter also referred to as “cells”) 263 arranged in a matrix. The lattice interval (pitch) and the rotation direction of each cell 263 may be different from each other. The shape of the cells 263 is not limited to a rectangle, the arrangement of the cells 263 is not limited to a matrix, and the number of cells 263 is not particularly limited. In the following description, the number of cells 263 along one side of the diffractive optical element 26 is also referred to as “pixel number PIX”. Further, when specifying one specific cell 263, the PIX number in the X direction and the Y direction is indicated, and the PIX number in the X direction and the Y direction indicates (1, 1) in the lower left cell 263 in the view shown in FIG. The standard is as 1).

  FIG. 5 is a diagram illustrating an example of a distribution characteristic of the lattice spacing of the diffractive optical element 26. FIG. 5 shows the distribution characteristics of the grating spacing of a plurality (300 in this example) of diffraction gratings along the X direction. For example, the distribution characteristic shown in FIG. 5 is a characteristic along a line (an example of a predetermined line) in the X direction passing through the center of the diffractive optical element 26.

  In the example shown in FIG. 5, the characteristic obtained from the diffractive optical element 26 having the following dimensional relationship is shown as an example. The diffractive optical element 26 is a rectangle having a size of 3 mm × 3 mm, the number of pixels PIX of the diffractive optical element 26 is 300, and the cell 263 is a rectangle having a size of 0.01 mm × 0.01 mm. In FIG. 5, a line connecting the lattice intervals of the cells 263 along the X direction is indicated by a solid line. In FIG. 5, an approximate curve by a second-order polynomial for each value (each plot point) of the lattice spacing for each cell 263 along the X direction is indicated by a broken line. The order of the polynomial relating to the approximate curve is arbitrary.

  As shown in FIG. 5, in the first embodiment, the distribution of the lattice spacing along the X direction has a characteristic that the lattice spacing is wider on the center side than on the end side. For example, as shown in FIG. 5, the lattice spacing at the PIX numbers “125 to 175” in the X direction is significantly larger than the lattice spacing at the PIX numbers “1 to 50” and “250 to 300” in the X direction. . In the example shown in FIG. 5, the distribution characteristic of the lattice spacing is symmetric with respect to the PIX number “150” in the X direction, but it may not be symmetric. The approximate curve takes a peak value at the PIX number “150” in the X direction (that is, the center in the X direction of the diffractive optical element 26), but the PIX number in the X direction that takes the peak value (that is, the diffractive optical element 26). (The position in the X direction) may be slightly shifted from the exact center as long as the position corresponds to the center of the diffractive optical element 26.

  The distribution characteristics shown in FIG. 5 indicate the characteristics along the line in the X direction passing through the center of the diffractive optical element 26 as described above. However, the diffractive optical element 26 is shown in FIG. 5 along an X direction line passing through an arbitrary position other than the center, or along an X direction line passing through an arbitrary position within a specific Y direction range. It may have the characteristics as shown. Further, the diffractive optical element 26 may have characteristics as shown in FIG. 5 along a line in the Y direction. In this case as well, the diffractive optical element 26 may have characteristics as shown in FIG. 5 along a line in the Y direction passing through the center of the diffractive optical element 26. Alternatively, the diffractive optical element 26 is shown in FIG. 5 along a Y-direction line passing through any position other than the center or along a Y-direction line passing through any position within a specific X-direction range. It may have the characteristics as shown. Alternatively, the diffractive optical element 26 may have characteristics as shown in FIG. 5 along a line in another direction (direction of a combination of the X direction and the Y direction) passing through the center of the diffractive optical element 26. . In these cases, “having the characteristics shown in FIG. 5” does not need to have the characteristics shown in FIG. 5 strictly, and the lattice spacing on the center side and the lattice spacing on the end side than the example shown in FIG. The difference may be large or small. That is, the polynomial coefficients of the approximate expression along each line may be different. In the following, it is assumed that the diffractive optical element 26 has characteristics as shown in FIG. 5 along a line (an example of a predetermined line) in an arbitrary direction passing through the center of the diffractive optical element 26 as an example.

  FIG. 6 is a diagram schematically illustrating the light intensity distribution of the nth-order diffracted light directed toward the illumination region 33. Each line 90 means that the larger the interval, the smaller the intensity of the n-th order diffracted light, and the smaller the interval, the greater the intensity of the n-order diffracted light.

Here, the general characteristic of diffraction can be expressed by the following approximate expression.
nλ / d = sinθi + sinθo
n: Diffraction order λ: Wavelength
d: grating spacing θi: incident light angle θo: diffracted light angle This equation means that the larger the grating distance d, the smaller the diffracted light angle, and the smaller the grating distance d, the larger the diffracted light angle.

  7A and 7B are diagrams showing the light intensity distribution in the illumination region 33, where FIG. 7A shows the light intensity distribution due to the 0th order transmitted light, FIG. 7B shows the distribution of the nth order diffracted light, and (C ) Is a diagram showing a light intensity distribution when the 0th order transmitted light and the nth order diffracted light are added together. In FIG. 7, the darker the gray scale, the smaller the light intensity is (ie, “dark”).

  Here, in general, the intensity of diffracted light decreases as the grating interval d increases. Therefore, it is known that when the grating interval is wide, the zeroth order transmitted light is strong and the diffracted light is weak, and conversely, when the grating interval is narrow, the zeroth order transmitted light is weak and the diffracted light becomes strong.

  As shown in FIG. 7A, since the 0th order transmitted light is inevitably generated in the diffractive optical element 26, the distribution of the light intensity of the illumination light in the illumination region 33 is the light of the illumination light by the 0th order transmitted light. Influenced by intensity distribution. In particular, since the intensity of light incident from the light source 25 is higher in the central region of the diffractive optical element 26 than in other regions (for example, Gaussian distribution), the zero-order transmission from the cell 263 in the central region of the diffractive optical element 26. The influence of light intensity distribution due to light increases. In the first embodiment, as shown in FIG. 5, since the lattice spacing is wider on the center side in the X direction than on the end side, the intensity of light directed from the cell 263 on the center side in the X direction to the illumination region 33 is The 0th order transmitted light is strong and the diffracted light is weak. Therefore, as shown in FIG. 7A, the light intensity distribution due to the 0th-order transmitted light is highest at the center of the illumination area 33 (center of the light source 25) as viewed in the Z direction. In addition, as shown in FIG. 7B, the intensity of the nth order diffracted light that illuminates the central region of the illumination area 33 is smaller than the intensity of the nth order diffracted light that illuminates the end area of the illumination area 33. That is, as shown in FIG. 7B, the light intensity distribution by the n-th order diffracted light has the lowest center of the illumination region 33 (the center of the light source 25) as viewed in the Z direction.

  Therefore, according to the first embodiment, as shown in FIG. 7C, the distribution of the light intensity when the 0th order transmitted light and the nth order diffracted light are added can be made uniform.

  Next, with reference to FIGS. 8 and 9, a modified example of the first embodiment will be described.

  FIG. 8 is a diagram showing the distribution of the lattice spacing along the X direction of the diffractive optical element 26 ′. This distribution characteristic is a characteristic (approximate curve by a second-order polynomial) along a line in the X direction passing through the center of the diffractive optical element 26 '. However, similarly to the above-described first embodiment, the diffractive optical element 26 ′ may have characteristics as shown in FIG. 8 even along lines in other directions. In FIG. 8, a broken line shows the case of the above-mentioned 1st Example, and a dashed-dotted line shows the case of this modification. FIG. 9 is a diagram schematically showing the light intensity distribution of the nth-order diffracted light directed toward the illumination region 33 by the diffractive optical element 26 ′. In FIG. 9, as in FIG. 6 showing the case of the first embodiment described above, each line 90 means that the larger the interval, the smaller the intensity of the n-th order diffracted light. It means that the strength of is large.

  In the present modification, the grating spacing of the diffractive optical element 26 'is such that the intensity distribution of the nth-order diffracted light in the illumination region 33 is uniform, as schematically shown in FIG. It is set to be. Specifically, in this modification, as shown in FIG. 8, the distribution characteristics of the lattice spacing along the line in the X direction are the same as those in the center side of the diffractive optical element 26 ′, as in the first embodiment. Is wider than the end side. However, in this modification, as shown in FIG. 8, the lattice spacing is narrower than that in the first embodiment. This tendency is particularly remarkable in the central region of the diffractive optical element 26 ′ along the X direction.

  According to this modified example, the distribution characteristic of the grating spacing along the X direction is larger at the center side of the diffractive optical element 26 'than at the end side, but is narrower than that of the first embodiment. The intensity distribution of the nth order diffracted light in the illumination region 33 can be made uniform. In other words, in the first embodiment described above, the distribution characteristics of the grating interval along the X direction are larger than those of the present modification, and the center side of the diffractive optical element 26 is more grating than the end side. Wide spacing. As a result, according to the first embodiment described above, it is possible to make the light intensity distribution uniform when the 0th order transmitted light and the nth order diffracted light are added together.

  In the first embodiment (including the modification) described above, the distribution of the lattice spacing of the diffractive optical element 26 is at a position corresponding to the center in the X direction of the diffractive optical element 26 as shown in FIGS. Take the peak value. Here, as described above, the position in the X direction of the diffractive optical element 26 taking the peak value does not need to coincide with the exact center of the diffractive optical element 26 in the X direction, and may slightly deviate from the exact center. For example, when the center of the diffractive optical element 26 and the center of the illumination area 33 (= the optical axis of the photographing optical system 72) are slightly shifted in the X direction, the position of the diffractive optical element 26 taking the peak value in the X direction is the exact center. To the direction toward the center of the illumination area 33. In this case, each grating interval of the diffractive optical element 26 may be set so that an approximate curve as shown in FIG. 5 takes a peak value at a position corresponding to the center of the illumination region 33, for example. The same applies to the case where the center of the diffractive optical element 26 and the center of the illumination region 33 are slightly shifted in other directions (directions other than the X direction). In any case, each grating interval of the diffractive optical element 26 is such that the approximate curve representing the distribution of the grating interval along the same direction corresponds to the center of the illumination region 33 (= the optical axis of the imaging optical system 72). It may be set to take a peak value at the position where

  Next, with reference to FIG. 10 thru | or FIG. 13, the illuminating device by 2nd Example is demonstrated.

  FIG. 10 is a diagram schematically showing an example of a lighting device in the second embodiment in cross-sectional view. In FIG. 10, an example of the illumination device in the second embodiment is indicated by reference numeral “100A”.

  The illumination device 100A differs from the illumination device 100 according to the first embodiment described above in that two sets of the light source 25 and the diffractive optical element 26 described in the first embodiment are arranged in the X direction.

  The first optical set 251 includes the light source 25 and the diffractive optical element 26, and the second optical set 252 includes the light source 25 and the diffractive optical element 26. The configurations of the light source 25 and the diffractive optical element 26 may be the same as those in the first embodiment described above.

  Since the illumination device 100A shown in FIG. 10 includes two optical sets (the first optical set 251 and the second optical set 252), the illumination in the illumination region 33 is performed even when the illumination region 33 is relatively large. The light intensity distribution of light can be made uniform in a desired manner. For example, by adjusting the X-direction interval Δx between the first optical set 251 and the second optical set 252, the light intensity distribution when the 0th order transmitted light and the nth order diffracted light are added is uniform in a desired manner. (See FIGS. 9 and 10).

  Note that the illumination device 100A illustrated in FIG. 10 includes two optical sets (a first optical set 251 and a second optical set 252), but may include three or more optical sets. In the illumination device 100A shown in FIG. 10, two optical sets (first optical set 251 and second optical set 252) are arranged in the X direction. However, the Y direction or a combination of the X direction and the Y direction is used. It may be arranged in the direction. Three or more optical sets may be arranged in an arrangement pattern other than a straight line.

  FIG. 11 is a diagram illustrating an example of light intensity distribution characteristics in the illumination region 33 obtained by the illumination device 100A. In FIG. 11, the horizontal axis represents the position of the illumination area 33 in the X direction, and the vertical axis represents the intensity. In FIG. 11, the position “x1” corresponds to the position of the first optical set 251 in the X direction, and the position “x2” corresponds to the position of the second optical set 252 in the X direction. In FIG. 11, (A) shows the distribution of the light intensity due to the 0th order transmitted light, (B) shows the distribution of the nth order diffracted light, and (C) shows the addition of the 0th order transmitted light and the nth order diffracted light. It is a figure which shows distribution of the light intensity when match | combining. The example illustrated in FIG. 11 illustrates a case where the distance Δx in the X direction between the first optical set 251 and the second optical set 252 is relatively large. In the example shown in FIG. 11, the X-direction interval Δx between the first optical set 251 and the second optical set 252 is the distribution of the light intensity when the 0th order transmitted light and the nth order diffracted light are added. It is set to be uniform as shown in C).

FIG. 12 is a diagram illustrating another example of the light intensity distribution characteristic in the illumination region 33 obtained by the illumination device 100A. In FIG. 12, the horizontal axis represents the position of the illumination area 33 in the X direction, and the vertical axis represents the intensity. In FIG. 12, the position “x3” corresponds to an intermediate position in the X direction between the first optical set 251 and the second optical set 252. In FIG. 12, (A) shows the distribution of the light intensity due to the 0th order transmitted light, (B) shows the distribution of the nth order diffracted light, and (C) shows the addition of the 0th order transmitted light and the nth order diffracted light. It is a figure which shows distribution of the light intensity when match | combining. The example shown in FIG. 12 shows a case where the distance Δx in the X direction between the first optical set 251 and the second optical set 252 is very small as shown in FIG. In the example shown in FIG. 12, the distance Δx in the X direction between the first optical set 251 and the second optical set 252 is the distribution of the light intensity when the 0th order transmitted light and the nth order diffracted light are added. As shown in C), the spherical intensity distribution is set. The spherical intensity distribution is expressed by the following expression, for example.
E (θ) = E0 × (cosθ) ²
Here, as shown in FIG. 13, θ is a straight line connecting the center of the first optical set 251 and the second optical set 252 in the X direction and each point of the illumination area 33 with respect to the optical axis. Represents an angle.

  Next, an example of a sensor for a biometric authentication device incorporating the illumination device 100 will be described with reference to FIGS.

  FIG. 14 is a diagram schematically showing an example of a biometric authentication device sensor incorporating the illumination device 100 in a top view. In FIG. 14, an example of a biometric authentication device sensor that incorporates the illumination device 100 is indicated by the reference numeral “70A”. In FIG. 14, the illumination region 33 is not shown. FIG. 15 is a diagram schematically showing an example of the substrate 261 including the diffractive optical element 26 in a top view. 16 is a cross-sectional view taken along line AA of FIG.

  The biometric authentication device sensor 70 </ b> A includes a photographing optical system 72 such as a camera, two light sources 25, and two diffractive optical elements 26. The two diffractive optical elements 26 are formed on a substrate 261, for example, as shown in FIG. Each diffractive optical element 26 is provided on the exit surface side of the light source 25 with respect to each of the two light sources 25. The two diffractive optical elements 26 are arranged symmetrically with respect to the optical axis of the photographing optical system 72. Each set of the diffractive optical element 26 and the light source 25 forms the illumination device 100.

  In the examples shown in FIGS. 14 to 16, each diffractive optical element 26 has the distribution characteristics of the grating spacing as described in the first embodiment (see FIGS. 5 and 8). If the offset between the optical axis of the light source 25 and the center of each diffractive optical element 26 is very small, it can be considered that the center of each diffractive optical element 26 is located on the optical axis of the light source 25. However, when the offset in the X direction between the optical axis of the light source 25 and the center of each diffractive optical element 26 is significant, each diffractive optical element 26 is only in the Y direction as described in the first embodiment. It may have a distribution characteristic of the lattice spacing. In this case, the distribution characteristic of the lattice spacing along the X direction may have a distribution characteristic (see FIG. 20) related to an asymmetric arrangement described later.

  FIG. 17 is a diagram schematically showing another example of the biometric authentication device sensor incorporating the illumination device 100 in a top view. In FIG. 17, an example of a biometric authentication device sensor that incorporates the illumination device 100 is indicated by a symbol “70B”. FIG. 18 is a diagram schematically showing still another example of the biometric device sensor incorporating the illumination device 100 in a top view. In FIG. 18, an example of a biometric authentication device sensor that incorporates the illumination device 100 is indicated by the reference numeral “70C”. 17 and 18, the diffractive optical elements 26 are arranged symmetrically with respect to the optical axis of the photographing optical system 72. Each set of the diffractive optical element 26 and the light source 25 forms the illumination device 100. As described above, the diffractive optical element 26 and the light source 25 may be arranged in an arbitrary manner symmetrically with respect to the optical axis of the imaging optical system 72 in an arbitrary number of sets.

  Next, with reference to FIG. 19 thru | or FIG. 21, the illuminating device by 3rd Example is demonstrated.

  FIG. 19 is a diagram schematically showing an example of a lighting device in the third embodiment in cross-sectional view. In FIG. 19, an example of the illumination device in the third embodiment is indicated by the reference numeral “100B”. In FIG. 3, the spread of light from the diffractive optical element 26 </ b> B toward the illumination region 33 is schematically indicated by a hatched range S.

  In the third embodiment, the optical axis I of the light source 25 and the optical axis of the diffractive optical element 26B are offset with respect to the optical axis I2 of the photographing optical system 72, and the principal ray I3 emitted from the center of the diffractive optical element 26 is inclined. This is different from the illumination device 100 according to the first embodiment described above. In addition, about the structure which may be the same as that of Example 1 mentioned above, the same referential mark is attached | subjected and description is abbreviate | omitted.

  The illumination device 100B includes a light source 25 and a diffractive optical element 26B.

  The diffractive optical element 26 </ b> B is provided between the illumination region 33 and the light source 25. The diffractive optical element 26B is formed by an aggregate (see FIG. 4) in which a plurality of diffraction gratings are two-dimensionally arranged. The center of the two-dimensional arrangement surface of the diffractive optical element 26 </ b> B is arranged on the optical axis of the light source 25. The diffractive optical element 26B may be the same as the diffractive optical element 26 in the first embodiment described above except that the distribution characteristic of the lattice spacing along the X direction is different as described later.

  The center of the diffractive optical element 26B is significantly offset in the X direction with respect to the optical axis I2 of the photographing optical system 72 as the optical axis I of the light source 25 and the optical axis I2 of the photographing optical system 72 are offset. doing. Significantly offset means that the optical axis I2 of the photographing optical system 72 is offset so as not to pass through the diffractive optical element 26B.

  FIG. 20 is a diagram illustrating an example of a distribution characteristic of the lattice spacing of the diffractive optical element 26B. FIG. 20 shows the distribution characteristics of the grating spacing of a plurality (300 in this example) of diffraction gratings along the X direction. For example, the distribution characteristic shown in FIG. 20 is a characteristic along a line (an example of a predetermined line) in the X direction passing through the center of the diffractive optical element 26B. However, the diffractive optical element 26B is shown in FIG. 20 along an X direction line passing through an arbitrary position other than the center or along an X direction line passing through an arbitrary position within a specific Y direction range. It may have the characteristics as shown.

  FIG. 21 is a diagram illustrating an example of a distribution characteristic of the lattice spacing of the diffractive optical element 26B. FIG. 21 shows the distribution characteristics of the grating spacing of a plurality (300 in this example) of diffraction gratings along the Y direction. For example, the distribution characteristics shown in FIG. 21 are characteristics along a Y-direction line (an example of a predetermined line) passing through the center of the diffractive optical element 26B. However, the diffractive optical element 26B is shown in FIG. 21 along a line in the Y direction passing through an arbitrary position other than the center, or along a line in the Y direction passing through an arbitrary position within a specific X direction range. It may have the characteristics as shown.

  In the example shown in FIGS. 20 and 21, as an example, the characteristics obtained from the diffractive optical element 26B having the following dimensional relationship are shown. The diffractive optical element 26B is a rectangle having a size of 3 mm × 3 mm, the number of pixels PIX of the diffractive optical element 26B is 300, and the cell 263 is a rectangle having a size of 0.01 mm × 0.01 mm. In FIGS. 20 and 21, lines connecting the lattice intervals of the cells 263 along the line in the X direction and the line in the Y direction are indicated by solid lines. In FIGS. 20 and 21, approximated curves using quadratic polynomials for each value (each plot point) of the lattice spacing for each cell 263 along the line in the X direction and the line in the Y direction are indicated by broken lines. . The order of the polynomial relating to the approximate curve is arbitrary.

  In the third example, as shown in FIG. 20, the distribution of the lattice spacing along the line in the X direction is such that the lattice spacing gradually increases from one end of the photographing optical system 72 closer to the optical axis I2 to the other end. Has the property of narrowing. In the example shown in FIG. 20, the distribution characteristic of the lattice spacing along the line in the X direction has a characteristic that the lattice spacing gradually narrows as the number of PIX in the X direction increases.

  Further, in the third embodiment, as shown in FIG. 21, the distribution of the lattice spacing along the line in the Y direction has a characteristic that the lattice spacing on the center side is wider than that on the end side. For example, as shown in FIG. 21, the lattice spacing at the PIX numbers “125 to 175” in the Y direction is significantly larger than the lattice spacing at the PIX numbers “1 to 50” and “250 to 300” in the Y direction. . In the example shown in FIG. 21, the distribution characteristic of the lattice spacing is symmetric with respect to the PIX number “150” in the Y direction, but it may not be symmetric.

  According to the third embodiment, even when the center of the diffractive optical element 26B is significantly offset in the X direction with respect to the optical axis I2 of the photographing optical system 72, as in the first embodiment, the 0th-order transmitted light and It is possible to make the light intensity distribution uniform when the n-th order diffracted light is added.

  In the third embodiment described above, the center of the diffractive optical element 26B is significantly offset in the X direction with respect to the optical axis I2 of the photographic optical system 72, while it is Y with respect to the optical axis I2 of the photographic optical system 72. There is no offset in the direction. However, the center of the diffractive optical element 26B may be significantly offset in both the X direction and the Y direction with respect to the optical axis I2 of the photographing optical system 72. In this case, the distribution characteristics of the lattice spacing along the Y direction may also be characteristics as shown in FIG.

  Next, with reference to FIGS. 22 to 26, an example of a sensor for a biometric authentication device incorporating the illumination device 100B will be described.

  FIG. 22 is a diagram schematically showing an example of a biometric authentication device sensor incorporating the illumination device 100B in top view. In FIG. 22, an example of a biometric authentication device sensor incorporating the illumination device 100 </ b> B is indicated by a sign “80A”. In FIG. 22, the illumination area 33 is not shown. FIG. 23 is a diagram schematically showing an example of the substrate 261B including the diffractive optical element 26B in a top view. 24 is a cross-sectional view taken along line BB in FIG.

  The biometric authentication device sensor 80A includes a photographing optical system 72, a light source 25, and a diffractive optical element 26B. For example, as shown in FIG. 23, the diffractive optical element 26B is formed on a substrate 261B. The diffractive optical element 26 </ b> B is provided on the exit surface side of the light source 25. The diffractive optical element 26B and the light source 25 form an illumination device 100B. In the examples shown in FIGS. 22 to 24, the diffractive optical element 26B has the distribution characteristics of the grating spacing as described in the third embodiment (see FIGS. 20 and 21).

  FIG. 25 is a diagram schematically showing another example of the biometric authentication device sensor incorporating the illumination device 100B in a top view. In FIG. 25, an example of a sensor for a biometric authentication device incorporating the illumination device 100B is indicated by reference numeral “80B”. FIG. 26 is a diagram schematically showing still another example of the biometric authentication device sensor incorporating the illumination device 100B in a top view. In FIG. 26, an example of a sensor for a biometric authentication device incorporating the illumination device 100B is indicated by reference numeral “80C”. 25 and 26, each diffractive optical element 26B is disposed asymmetrically with respect to the optical axis of the imaging optical system 72. Each set of the diffractive optical element 26B and the light source 25 forms an illumination device 100B. As described above, the diffractive optical element 26 </ b> B and the light source 25 may be arranged in an arbitrary manner with an arbitrary number of sets and asymmetrically with respect to the optical axis of the imaging optical system 72.

  Next, an example of a biometric authentication device in one embodiment will be described with reference to FIGS.

  FIG. 27 is a block diagram illustrating an example of a biometric authentication device. A biometric authentication device 600 illustrated in FIG. 27 includes an illumination optical system 23, a photographing optical system 72, an LED control unit 63, an image acquisition unit 66, a biometric information detection unit 68, a collation unit 71, a storage unit 73, a determination unit 74, and a result. A display unit 75 is included. The storage unit 73 stores a biometric template prepared in advance, and the collation unit 71 collates the biometric information detected by the biometric information detection unit 68 with the biometric template. The result display unit 75 displays the collation result of the collation unit 71 or the biological image.

  The illumination optical system 23 includes the illumination device 100. However, the illumination optical system 23 may include the illumination device 100A or 100B. Further, the illumination optical system 23 and the photographing optical system 72 may be formed by any of the above-described biometric authentication device sensors 70A to 70C and 80A to 80C.

  When the user positions the palm, which is an example of a living body, in the illumination area 33, the biometric authentication device 600 detects the authentication target, and the LED control unit 63 turns on the light source 25 of the illumination optical system 23. Thereby, the light source 25 irradiates the illumination area 33 with light via the diffractive optical element 26. The imaging optical system 72 images the living body (the palm in this example) in the illumination area 33, and the image acquisition unit 66 acquires the captured input image. The biological information detection unit 68 detects biological information unique to the user based on the input image. The collation unit 71 collates the detected biometric information with the biometric template stored in advance in the storage unit 73. The determination unit 74 determines whether or not the user is a valid user based on the collation result. The result display unit 75 displays the collation result in the collation unit 71 or the determination result of the determination unit 74 on the display unit. The result display unit 75 displays, for example, a verification result message indicating whether or not the detected biometric information matches the biometric template on the display unit. The result display unit 75 is an example of an output unit that outputs a collation result in the collation unit 71. The output unit that outputs the collation result is not limited to the result display unit 75 that displays the collation result, and may be formed by, for example, a voice synthesis unit that outputs the collation result by voice. Further, the determination unit 74 may be omitted, and the function of the determination unit 74 may be realized by the collation unit 71.

  FIG. 28 is a block diagram illustrating an example of the configuration of a computer. The biometric authentication device 600 shown in FIG. 27 may be formed by the computer 300 shown in FIG. A computer 300 shown in FIG. 28 may be a general-purpose computer such as a personal computer. The computer 300 may include a CPU 301, a storage unit 302, a keyboard 303 that is an example of an input unit, an interface 305, and a display unit 306 that is an example of an output unit. In this example, the CPU 301, the storage unit 302, the keyboard 303, the interface 305, and the display unit 306 are connected via the bus 307, but the computer 300 is not limited to the configuration connected via the bus 307. The photographing optical system 72 and the illumination optical system 23 are connected to the interface 305, for example.

  The storage unit 302 stores programs executed by the CPU 301, various data including a biological template, and the like. The storage unit 302 may be formed of a storage device such as a memory or an HDD (Hard Disk Drive). The CPU 301 controls the entire computer 300 by executing a program stored in the storage unit 302. The CPU 301 executes all or one of the LED control unit 63, the image acquisition unit 66, the biological information detection unit 68, the collation unit 71, the storage unit 73, the determination unit 74, and the result display unit 75 in FIG. 27 by executing the program. The function of the part can be realized. The CPU 301 can realize the function of the collation unit 71 by executing a program, for example. The storage unit 302 also realizes the function of the storage unit 73.

  A keyboard 303 is used to input commands and data to the CPU 301. The interface 305 is used for connection between the computer 300 and an external device. The display unit 306 displays various data for the user (or operator) of the computer 300 under the control of the CPU 301. Various data displayed by the display unit 306 may include an acquired input image, a message of a matching result, and the like.

  Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes can be made within the scope described in the claims. It is also possible to combine all or a plurality of the components of the above-described embodiments.

  For example, in each of the above-described embodiments, biometric authentication is not limited to palm vein pattern authentication, but biometric information such as finger vein patterns, fingerprint patterns, palm print patterns, eye iris patterns, facial features, and the like. There may be.

  In the second embodiment described above, a diffractive optical element 26 ′ or a diffractive optical element 26 B may be used instead of the diffractive optical element 26.

In addition, the following additional remarks are disclosed regarding the above Example.
(Appendix 1)
A light source that illuminates the illumination area;
A diffractive optical element provided between the illumination region and the light source and having a plurality of diffraction gratings arranged two-dimensionally;
The illumination device in which the distribution of the grating spacing of the plurality of diffraction gratings along a predetermined line in the two-dimensional arrangement plane of the diffractive optical element has a characteristic that the grating spacing is wider on the center side than on the end side.
(Appendix 2)
The diffractive optical element is disposed with respect to the light source such that the two-dimensional arrangement surface is perpendicular to the optical axis of the light source and the optical axis of the light source passes through the center of the diffractive optical element;
The illuminating device according to claim 1, wherein an optical axis of the light source passes through a center of the illumination area.
(Appendix 3)
The illuminating device according to attachment 2, wherein the predetermined line includes two lines orthogonal to each other through the center of the diffractive optical element.
(Appendix 4)
4. The illumination device according to claim 1, wherein an approximate curve with respect to a distribution of grating intervals of the plurality of diffraction gratings along the predetermined line has the characteristic.
(Appendix 5)
The illumination device according to appendix 4, wherein the approximate curve has a peak value at a position corresponding to a center of the diffractive optical element.
(Appendix 6)
The diffractive optical element is disposed with respect to the illumination area in such a relationship that a straight line passing through the center of the illumination area and parallel to the optical axis of the light source passes through the diffractive optical element.
The illumination device according to appendix 4, wherein the approximate curve has a peak value at a position corresponding to a center of the illumination area.
(Appendix 7)
The illumination device according to any one of appendices 1 to 6, wherein the diffractive optical element is an assembly of diffraction gratings in which the plurality of diffraction gratings having different grating intervals and rotation directions are two-dimensionally arranged.
(Appendix 8)
The grating intervals and rotation directions of the plurality of diffraction gratings are distributions of the light intensity over the entire illumination area, and the light intensity distributions of the 0th order transmitted light and the ± 1st order transmitted light are based only on the first order transmitted light. Item 8. The illumination device according to item 7, which is set to be more uniform than the distribution of light intensity.
(Appendix 9)
A light source that illuminates the illumination area;
A diffractive optical element provided between the illumination region and the light source and having a plurality of diffraction gratings arranged two-dimensionally;
The optical axis of the light source is offset in the direction of a predetermined line with respect to the center of the illumination area,
The distribution of the grating spacing of the plurality of diffraction gratings along the predetermined line in the two-dimensional arrangement surface of the diffractive optical element is such that the grating spacing gradually increases from one end closer to the center of the illumination area toward the other end. A lighting device having a narrowing characteristic.
(Appendix 10)
The diffractive optical element is disposed with respect to the light source such that the two-dimensional arrangement plane is perpendicular to the optical axis of the light source and the optical axis of the light source passes through the center of the diffractive optical element. The lighting device according to attachment 9.
(Appendix 11)
The illuminating device according to claim 9 or 10, wherein an approximate curve for a distribution of grating intervals of the plurality of diffraction gratings along the predetermined line has a peak value at a position corresponding to one end of the illumination region.
(Appendix 12)
A light source that illuminates the illumination area;
A set of diffraction gratings provided between the illumination region and the light source and two-dimensionally arranged with a plurality of diffraction gratings having different grating intervals and rotation directions;
The grating intervals and rotation directions of the plurality of diffraction gratings are light intensity distributions throughout the illumination area, and the light intensity distributions of the 0th order transmitted light and the ± 1st order transmitted light depend only on the first order transmitted light. An illumination device that is set to be more uniform than the distribution of light intensity.
(Appendix 13)
A plurality of lighting devices according to any one of appendices 1 to 13 are provided for the lighting area,
The interval between the plurality of sets is set such that the distribution of light intensity over the entire illumination area is uniform or spherical intensity distribution.
(Appendix 14)
A light source that illuminates the illumination area;
A diffractive optical element that is provided between the illumination region and the light source and in which a plurality of diffraction gratings are two-dimensionally arranged, and having a grating interval of the plurality of diffraction gratings along a predetermined line in a two-dimensional arrangement surface A diffractive optical element whose distribution is such that the center side has a wider grating spacing than the end side;
An imaging optical system for imaging the illumination area;
A biometric authentication apparatus comprising: a verification unit that performs biometric authentication based on an image captured by the imaging optical system.
(Appendix 15)
An optical axis offset in the direction of a predetermined line with respect to the center of the illumination area, provided between the light source that irradiates light to the illumination area, the illumination area and the light source, and a plurality of diffraction gratings are two-dimensional The diffractive optical element is arranged, and a distribution of grating intervals of the plurality of diffraction gratings along the predetermined line in a two-dimensional arrangement plane is from one end closer to the center of the illumination area toward the other end. A diffractive optical element having a characteristic that the grating interval is gradually narrowed;
An imaging optical system for imaging the illumination area;
A biometric authentication apparatus comprising: a verification unit that performs biometric authentication based on an image captured by the imaging optical system.
(Appendix 16)
The diffractive optical element is disposed with respect to the light source such that the two-dimensional arrangement plane is perpendicular to the optical axis of the light source and the optical axis of the light source passes through the center of the diffractive optical element. The biometric authentication device according to appendix 13 or 14.
(Appendix 17)
A light source that illuminates the illumination area;
A diffractive optical element that is provided between the illumination region and the light source and in which a plurality of diffraction gratings are two-dimensionally arranged, and having a grating interval of the plurality of diffraction gratings along a predetermined line in a two-dimensional arrangement surface A diffractive optical element whose distribution is such that the center side has a wider grating spacing than the end side;
A biometric authentication device sensor comprising: a photographing optical system that images the illumination area.
(Appendix 18)
An optical axis offset in the direction of a predetermined line with respect to the center of the illumination area, provided between the light source that irradiates light to the illumination area, the illumination area and the light source, and a plurality of diffraction gratings are two-dimensional The diffractive optical element is arranged, and a distribution of grating intervals of the plurality of diffraction gratings along the predetermined line in a two-dimensional arrangement plane is from one end closer to the center of the illumination area toward the other end. A diffractive optical element having a characteristic that the grating interval is gradually narrowed;
A biometric authentication device sensor comprising: a photographing optical system that images the illumination area.

25 Light source 26, 26 ', 26B Diffractive optical element 33 Illumination area 71 Collation unit 72 Imaging optical system 100, 100A, 100B Illumination device 600 Biometric authentication device

Claims (9)

A light source that illuminates the illumination area;
A diffractive optical element provided between the illumination region and the light source and having a plurality of diffraction gratings arranged two-dimensionally;
The illumination device in which the distribution of the grating spacing of the plurality of diffraction gratings along a predetermined line in the two-dimensional arrangement plane of the diffractive optical element has a characteristic that the grating spacing is wider on the center side than on the end side. The diffractive optical element is disposed with respect to the light source such that the two-dimensional arrangement surface is perpendicular to the optical axis of the light source and the optical axis of the light source passes through the center of the diffractive optical element;
The lighting device according to claim 1, wherein an optical axis of the light source passes through a center of the illumination area.   The illumination device according to claim 2, wherein the predetermined line includes two lines orthogonal to each other through the center of the diffractive optical element.   The illuminating device according to claim 1, wherein an approximate curve for a distribution of grating intervals of the plurality of diffraction gratings along the predetermined line has the characteristic.   The illumination device according to claim 4, wherein the approximate curve has a peak value at a position corresponding to a center of the diffractive optical element. A light source that illuminates the illumination area;
A diffractive optical element provided between the illumination region and the light source and having a plurality of diffraction gratings arranged two-dimensionally;
The optical axis of the light source is offset in the direction of a predetermined line with respect to the center of the illumination area,
The distribution of the grating spacing of the plurality of diffraction gratings along the predetermined line in the two-dimensional arrangement surface of the diffractive optical element is such that the grating spacing gradually increases from one end closer to the center of the illumination area toward the other end. A lighting device having a narrowing characteristic.   The illumination device according to claim 6, wherein an approximate curve for a distribution of grating intervals of the plurality of diffraction gratings along the predetermined line has a peak value at a position corresponding to one end of the illumination region. A light source that illuminates the illumination area;
A diffractive optical element that is provided between the illumination region and the light source and in which a plurality of diffraction gratings are two-dimensionally arranged, and having a grating interval of the plurality of diffraction gratings along a predetermined line in a two-dimensional arrangement surface A diffractive optical element whose distribution is such that the center side has a wider grating spacing than the end side;
An imaging optical system for imaging the illumination area;
A biometric authentication apparatus comprising: a verification unit that performs biometric authentication based on an image captured by the imaging optical system. An optical axis offset in the direction of a predetermined line with respect to the center of the illumination area, provided between the light source that irradiates light to the illumination area, the illumination area and the light source, and a plurality of diffraction gratings are two-dimensional The diffractive optical element is arranged, and a distribution of grating intervals of the plurality of diffraction gratings along the predetermined line in a two-dimensional arrangement plane is from one end closer to the center of the illumination area toward the other end. A diffractive optical element having a characteristic that the grating interval is gradually narrowed;
An imaging optical system for imaging the illumination area;
A biometric authentication apparatus comprising: a verification unit that performs biometric authentication based on an image captured by the imaging optical system.